28 



It was found in exposed situations. — G. B. S. 

 Chiton Frembleii. Chit. testd oblongd, complanatd, olivaceO' 

 J'uscii, Uneis albido-viridibus varia ; valvcB anticce radiis elevatis 

 subgranosia ; intermediarum marginibus angulosis, areis lateralibua 

 biradiatis, radiis subgranosis, interstitiis longitudinaliter subsul- 

 catis; limbo setis brevibusjrequentibus obsito: long. \^,lat. ] poli. 

 Hab. in Sinu Valparaiso. 



This species difFers from Chit. setiger, King, in being much flatter, 

 in the more angular margins of its intermediate valves, and in its 

 more numerous and miich shorter bristles. 



It was found only on one exposed rock covered by a small species 

 of Fucus.—V^. J. B. 



****** Ligamento marginis piloso. 

 Chiton scabriculus. Chit. testą ovali, planiuscuM, cinered, 

 albido-variegatd ; valvd anticd, areis lateralibus valvarum inter- 

 mediarum et parte posticd valvce posticce radialbn scabroso- 

 lineatis ; valvis intermediis et parte anticd valvce posticce longi- 

 tudinaliter sulcatis ; limbo piloso, cinereo, riifo-articulato : long. 

 1^, lat. į poli. 

 Hab. ad littora Americae Centralis. (Guacomayo and Puerto 



Portrero.) 

 Found under stones. — G. B. S. 



******* Ligamento marginis fasciculato-piloso. 

 Chiton retusus. Chit. testą oblongii, postice relusd, pallescente ; 

 valva anticd, areis lateralibus valvarum intermediarum et valvce 

 posticcE ared posticd turgidis, r adiato- sulcatis ; areis centralibus 

 valvarum intermediarum et ared anticd valvcB posticce sulcato- 

 asperis ; ligamento marginis Jasciculis pilorum minimis plurimis : 

 long. l-iV, lat. J^ poli. 

 Hab. ad oras Americae Centralis. (Guacomayo and Puerto Por- 

 trero.)— G. B. S. 



Genus Placunanomia. 

 Testą adhaerens, subaeąuivalvis, irregularis, complanata, marginėm 

 versus plicata, internė vitrea. Cardo internus, dentibus duobus 

 elongatis, crassis, subcurvis, divaricatis, basi convergentibus in 

 valva inferiore, suleis duobus liganientiferis in superiore. FaZua 

 inferior cardinem versus superficialiter irregulariter externe fissu- 

 rata, organo adhaesionis subosseo inter testae laminas inserto et 

 externė fissuram implente. Impressio muscularis in utraque valvS 

 subcentralis. In valva, superiore organi adhaesionis impressio super- 

 addita. 



This interesting genus partakes of the characters of the genera 

 Ostrea, Flicatula, Placuna, and Anomia. It may be regarded as 

 the connecting link betvveen the two latter. With an arrangement 

 of the hinge approaching very nearly to that of Placuna, it has the 

 distinguishing organization of Anomia, while the external appear- 

 ance of the shell, especially if view^ed in situ, bears the strongest 

 reseniblance to a Plicatula or some of the plicated Oysters. The 

 organ of adhesion, which in its bony character (for it is more bony 



